Ambient condition detection systems, such as fire detection systems are known to be useful in providing early warnings of potentially dangerous conditions such as fires. One such system as disclosed and claimed in Tice et al. U.S. Pat. No. 4,916,432 entitled Smoke and Fire Detection System Communication assigned to the Assignee hereof. The disclosure thereof is incorporated by reference herein.
The system of the Tice et al. patent, as well as many other known systems, make use of a master-slave communication protocol. In such systems, a common control element is coupled via a communication link to a plurality of ambient condition detectors or transducers.
The control element transmits commands to addressed detectors, devices, groups of detectors or devices. The devices or detectors respond with transmissions of information pertaining to status or detect an ambient condition which the control element analyzes and acts upon as appropriate.
While the master-slave communication protocol is useful and effective, its usefulness is at times limited by an inability to respond to equipment or transmission failures by operating in a degraded mode.
One known attempt to provide operation in a degraded mode, requires that the devices each be assigned a unique serial number. In the event that for some reason the control element is unable to communicate with a respective device, and the device detects an ambient condition calling for an alarm, the respective device can communicate directly with an output element such as a horn or a strobe thereby continuing to be able to provide an indication of the existence of a potential fire. Another known system permits some of the processors to be programmed to transmit information to other processors, as opposed to the control element. The other processors are in turn programmed to respond to the transmitted information.
A disadvantage of known systems is their limited flexibility. Further, the systems which permit specific devices to be programmed to transmit information to other devices which are in turn programmed to respond to that information require extensive programming, which can be very device specific. The communication protocol in such systems requires very long transmissions between devices.
Hence, there continues to be a need for communication systems useable in multi-processor environments wherein various of the processors are able to readily communicate among one another, in addition to being able to communicate with a common control element if such is present. It would be desirable to implement such a communication process using software which is common to all of the processors. It would also be preferable if all of the processors in the system have the ability to intercommunicate among one another as well as to be able to communicate with the common control element, assuming such was present. Finally, it would be preferable if each of the processors was able to respond to communications from another processor with or without additional information being provided by perhaps second, third or fourth additional processors in the system.